Legged robots have better performance on discontinuous terrain than that of wheeled robots. However, the dynamic trotting and balance control of a quadruped robot is still a challenging problem, especially when the ro...Legged robots have better performance on discontinuous terrain than that of wheeled robots. However, the dynamic trotting and balance control of a quadruped robot is still a challenging problem, especially when the robot has multi-joint legs. This paper presents a three-dimensional model of a quadruped robot which has 6 Degrees of Freedom （DOF） on torso and 5 DOF on each leg. On the basis of the Spring-Loaded Inverted Pendulum （SLIP） model, body control algorithm is discussed in the first place to figure out how legs work in 3D trotting. Then, motivated by the principle of joint function separation and introducing certain biological characteristics, two joint coordination approaches are developed to produce the trot and provide balance. The robot reaches the highest speed of 2.0 m.s-1, and keeps balance under 250 Kg.m.s-1 lateral disturbance in the simulations. The effectiveness of these approaches is also verified on a prototype robot which runs to 0.83 m.s-1 on the treadmill, The simulations and experiments show that legged robots have good biological properties, such as the ground reaction force, and spring-like leg behavior.展开更多
The realization of a high-speed running robot is one of the most challenging problems in developing legged robots. The excellent performance of cheetahs provides inspiration for the control and mechanical design of su...The realization of a high-speed running robot is one of the most challenging problems in developing legged robots. The excellent performance of cheetahs provides inspiration for the control and mechanical design of such robots. This paper presents a three-dimensional model of a cheetah that predicts the locomotory behaviors of a running cheetah. Applying biological knowledge of the neural mechanism, we control the muscle flexion and extension during the stance phase, and control the positions of the joints in the flight phase via a PD controller to minimize complexity. The proposed control strategy is shown to achieve similar locomotion of a real cheetah. The simulation realizes good biological properties, such as the leg retraction, ground reaction force, and spring-like leg behavior. The stable bounding results show the promise of the controller in high-speed locomotion. The model can reach 2.7 m-s^-1 as the highest speed, and can accelerate from 0 to 1.5 m-s^-1 in one stride cycle. A mechanical structure based on this simulation is designed to demonstrate the control approach, and the most recently developed hindlimb controlled by the proposed controller is presented in swinging-leg experiments and jump-force experiments.展开更多
This paper presents a novel, legged robot, Abigaille-Ⅲ, which is a hexapod actuated by 24 miniature gear motors. This robot uses dual-layer dry adhesives to climb smooth, vertical surfaces. Because dry adhesives are ...This paper presents a novel, legged robot, Abigaille-Ⅲ, which is a hexapod actuated by 24 miniature gear motors. This robot uses dual-layer dry adhesives to climb smooth, vertical surfaces. Because dry adhesives are passive and stick to various surfaces, they have advantages over mechanisms such as suction, claws and magnets. The mechanical design and posture of Abigaille-Ⅲ were optimized to reduce pitchback forces during vertical climbing. The robot＇s electronics were designed around a Field Programmable Gate Array, producing a versatile computing architecture. The robot was reconfigured for vertical climbing with both 5 and 6 legs, and with 3 or 4 motors per leg, without changes to the electronic hardware. Abigaille-Ⅲ demonstrated dexterity through vertical climbing on uneven surfaces, and by transferring between horizontal and vertical sur- faces. In endurance tests, Abigaille-Ⅲ completed nearly 4 hours of continuous climbing and over 7 hours of loitering, showing that dry adhesive climbing systems can be used for extended missions.展开更多
A quadruped robot with four actuated hip joints and four passive highly compliant knee joints is used to demonstrate the potential of underactuation from two standpoints： learning locomotion and perception. First, we...A quadruped robot with four actuated hip joints and four passive highly compliant knee joints is used to demonstrate the potential of underactuation from two standpoints： learning locomotion and perception. First, we show that： （i） forward locomotion on flat ground can be learned rapidly （minutes of optimization time）; （ii） a simulation study reveals that a passive knee configuration leads to faster, more stable, and more efficient locomotion than a variant of the robot with active knees; （iii） the robot is capable of learning turning gaits as well. The merits of underactuation （reduced controller complexity, weight, and energy consumption） are thus preserved without compromising the versatility of behavior. Direct optimization on the reduced space of active joints leads to effective learning of model-free controllers. Second, we find passive compliant joints with po- tentiometers to effectively complement inertial sensors in a velocity estimation task and to outperform inertial and pressure sensors in a terrain detection task. Encoders on passive compliant joints thus constitute a cheap and compact but powerful sensing device that gauges joint position and force/torque, and -- if mounted more distally than the last actuated joints in a legged robot -- it delivers valuable information about the interaction of the robot with the ground.展开更多
In this paper a bio-inspired approach of velocity control for a quadruped robot running with a bounding gait on compliant legs is set up. The dynamic properties ofa sagittal plane model of the robot are investigated. ...In this paper a bio-inspired approach of velocity control for a quadruped robot running with a bounding gait on compliant legs is set up. The dynamic properties ofa sagittal plane model of the robot are investigated. By analyzing the stable fixed points based on Poincare map, we find that the energy change of the system is the main source for forward velocity adjustment. Based on the analysis of the dynamics model of the robot, a new simple linear running controller is proposed using the energy control idea, which requires minimal task level feedback and only controls both the leg torque and ending impact angle. On the other hand, the functions of mammalian vestibular reflexes are discussed, and a reflex map between forward velocity and the pitch movement is built through statistical regression analysis. Finally, a velocity controller based on energy control and vestibular reflexes is built, which has the same structure as the mammalian nervous mechanism for body posture control. The new con- troller allows the robot to run autonomously without any other auxiliary equipment and exhibits good speed adjustment capa- bility. A series simulations and experiments were set to show the good movement agility, and the feasibility and validity of the robot system.展开更多
Legged robots relying on dry adhesives for vertical climbing are required to preload their feet against the wall to increase contact surface area and consequently maximize adhesion force. Preloading a foot causes a re...Legged robots relying on dry adhesives for vertical climbing are required to preload their feet against the wall to increase contact surface area and consequently maximize adhesion force. Preloading a foot causes a redistribution of forces in the entire robot, including contact forces between the other feet and the wall. An inappropriate redistribution of these forces can cause irreparable detachment of the robot from the vertical surface. This paper investigates an optimal preloading and detaching strategy that minimizes energy consumption, while retaining safety, during locomotion on vertical surfaces. The gait of a six-legged robot is planned using a quasi-static model that takes into account both the structure of the robot and the character- istics of the adhesive material. The latter was modelled from experimental data collected for this paper. A constrained optimi- zation routine is used, and its output is a sequence of optimal posture and motor torque set-points.展开更多
Current door-opening methods are mainly developed on tracked, wheeled and biped robots by applying multi-DOF manipulators and vision systems. However, door-opening methods for six-legged robots are seldom studied, esp...Current door-opening methods are mainly developed on tracked, wheeled and biped robots by applying multi-DOF manipulators and vision systems. However, door-opening methods for six-legged robots are seldom studied, especially using 0-DOF tools to operate and only force sensing to detect. A novel door-opening method for six-legged robots is developed and imple- mented to the six-parallel-legged robot. The kinematic model of the six-parallel-legged robot is established and the model of measuring the positional relationship between the robot and the door is proposed. The measurement model is completely based on only force sensing. The real- time trajectory planning method and the control strategy are designed. The trajectory planning method allows the maximum angle between the sagittal axis of the robot body and the normal line of the door plane to be 45°. A 0-DOF tool mounted to the robot body is applied to operate. By integrating with the body, the tool has 6 DOFs and enough workspace to operate. The loose grasp achieved by the tool helps release the inner force in the tool. Experiments are carried out to validate the method. The results show that the method is effective and robust in opening doors wider than 1 m. This paper proposes a novel door-opening method for six-legged robots, which notably uses a O-DOF tool and only force sensing to detect and open the door.展开更多
基金Acknowledgment This work was supported by the National Hi-tech Research and Development Program of China （863 Program, Grant No. 2011AA040701）, and the National Natural Science Foundation of China （No. 61375097, No. 61175107）
文摘Legged robots have better performance on discontinuous terrain than that of wheeled robots. However, the dynamic trotting and balance control of a quadruped robot is still a challenging problem, especially when the robot has multi-joint legs. This paper presents a three-dimensional model of a quadruped robot which has 6 Degrees of Freedom （DOF） on torso and 5 DOF on each leg. On the basis of the Spring-Loaded Inverted Pendulum （SLIP） model, body control algorithm is discussed in the first place to figure out how legs work in 3D trotting. Then, motivated by the principle of joint function separation and introducing certain biological characteristics, two joint coordination approaches are developed to produce the trot and provide balance. The robot reaches the highest speed of 2.0 m.s-1, and keeps balance under 250 Kg.m.s-1 lateral disturbance in the simulations. The effectiveness of these approaches is also verified on a prototype robot which runs to 0.83 m.s-1 on the treadmill, The simulations and experiments show that legged robots have good biological properties, such as the ground reaction force, and spring-like leg behavior.
基金Acknowledgments This work is supported by the National Hi-tech Research and Development Program of China （863 Program, Grant no. 2011AA0403837002）, the National Natural Science Foundation of China （No. 61005076, No. 61175107）, and the Self-Planned Task （No. SKLRS201006B） of the State Key Laboratory of Ro- botics and System （HIT）.
文摘The realization of a high-speed running robot is one of the most challenging problems in developing legged robots. The excellent performance of cheetahs provides inspiration for the control and mechanical design of such robots. This paper presents a three-dimensional model of a cheetah that predicts the locomotory behaviors of a running cheetah. Applying biological knowledge of the neural mechanism, we control the muscle flexion and extension during the stance phase, and control the positions of the joints in the flight phase via a PD controller to minimize complexity. The proposed control strategy is shown to achieve similar locomotion of a real cheetah. The simulation realizes good biological properties, such as the leg retraction, ground reaction force, and spring-like leg behavior. The stable bounding results show the promise of the controller in high-speed locomotion. The model can reach 2.7 m-s^-1 as the highest speed, and can accelerate from 0 to 1.5 m-s^-1 in one stride cycle. A mechanical structure based on this simulation is designed to demonstrate the control approach, and the most recently developed hindlimb controlled by the proposed controller is presented in swinging-leg experiments and jump-force experiments.
文摘This paper presents a novel, legged robot, Abigaille-Ⅲ, which is a hexapod actuated by 24 miniature gear motors. This robot uses dual-layer dry adhesives to climb smooth, vertical surfaces. Because dry adhesives are passive and stick to various surfaces, they have advantages over mechanisms such as suction, claws and magnets. The mechanical design and posture of Abigaille-Ⅲ were optimized to reduce pitchback forces during vertical climbing. The robot＇s electronics were designed around a Field Programmable Gate Array, producing a versatile computing architecture. The robot was reconfigured for vertical climbing with both 5 and 6 legs, and with 3 or 4 motors per leg, without changes to the electronic hardware. Abigaille-Ⅲ demonstrated dexterity through vertical climbing on uneven surfaces, and by transferring between horizontal and vertical sur- faces. In endurance tests, Abigaille-Ⅲ completed nearly 4 hours of continuous climbing and over 7 hours of loitering, showing that dry adhesive climbing systems can be used for extended missions.
基金Acknowledgment Matej Hoffmann was supported by the Swiss National Science Foundation project ＂From locomotion to cognition＂ （Grant No. 200020-122279/1）. Jakub Simanek was supported by the Grant Agency of the CTU in Prague （Grant No. SGS 15/163/OHK3/2T/13）. Matej Hoffmann would like to thank Roll Pfeifer for continuous support of this project and to the collaborators that contributed to the investigations that laid the foundations for this work, in particular Fumiya Iida, Michal Reinstein, Nico Schmidt, and students Stefan Hutter, Richard Meuris, Nicolas Ruegg, Urs Fassler, and Mathias Weyland. We would also like to thank Koh Hosoda for the idea that passive joints may increase the overall ground contact duration of individual legs and Nadja Schilling for a discussion of the ＂template＂ of leg morphology in mammalian running. Finally, we are indebted to Michal Reinstein and Kenichi Narioka for valuable comments on the manuscript.
文摘A quadruped robot with four actuated hip joints and four passive highly compliant knee joints is used to demonstrate the potential of underactuation from two standpoints： learning locomotion and perception. First, we show that： （i） forward locomotion on flat ground can be learned rapidly （minutes of optimization time）; （ii） a simulation study reveals that a passive knee configuration leads to faster, more stable, and more efficient locomotion than a variant of the robot with active knees; （iii） the robot is capable of learning turning gaits as well. The merits of underactuation （reduced controller complexity, weight, and energy consumption） are thus preserved without compromising the versatility of behavior. Direct optimization on the reduced space of active joints leads to effective learning of model-free controllers. Second, we find passive compliant joints with po- tentiometers to effectively complement inertial sensors in a velocity estimation task and to outperform inertial and pressure sensors in a terrain detection task. Encoders on passive compliant joints thus constitute a cheap and compact but powerful sensing device that gauges joint position and force/torque, and -- if mounted more distally than the last actuated joints in a legged robot -- it delivers valuable information about the interaction of the robot with the ground.
文摘In this paper a bio-inspired approach of velocity control for a quadruped robot running with a bounding gait on compliant legs is set up. The dynamic properties ofa sagittal plane model of the robot are investigated. By analyzing the stable fixed points based on Poincare map, we find that the energy change of the system is the main source for forward velocity adjustment. Based on the analysis of the dynamics model of the robot, a new simple linear running controller is proposed using the energy control idea, which requires minimal task level feedback and only controls both the leg torque and ending impact angle. On the other hand, the functions of mammalian vestibular reflexes are discussed, and a reflex map between forward velocity and the pitch movement is built through statistical regression analysis. Finally, a velocity controller based on energy control and vestibular reflexes is built, which has the same structure as the mammalian nervous mechanism for body posture control. The new con- troller allows the robot to run autonomously without any other auxiliary equipment and exhibits good speed adjustment capa- bility. A series simulations and experiments were set to show the good movement agility, and the feasibility and validity of the robot system.
文摘Legged robots relying on dry adhesives for vertical climbing are required to preload their feet against the wall to increase contact surface area and consequently maximize adhesion force. Preloading a foot causes a redistribution of forces in the entire robot, including contact forces between the other feet and the wall. An inappropriate redistribution of these forces can cause irreparable detachment of the robot from the vertical surface. This paper investigates an optimal preloading and detaching strategy that minimizes energy consumption, while retaining safety, during locomotion on vertical surfaces. The gait of a six-legged robot is planned using a quasi-static model that takes into account both the structure of the robot and the character- istics of the adhesive material. The latter was modelled from experimental data collected for this paper. A constrained optimi- zation routine is used, and its output is a sequence of optimal posture and motor torque set-points.
基金Supported by National Natural Science Foundation of China(Grant Nos.U1613208,51335007)National Basic Research Program of China(973 Program,Grant No.2013CB035501)+1 种基金Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.51421092)Science and Technology Commission of Shanghai-based ‘‘Innovation Action Plan’’ Project(Grant No.16DZ1201001)
文摘Current door-opening methods are mainly developed on tracked, wheeled and biped robots by applying multi-DOF manipulators and vision systems. However, door-opening methods for six-legged robots are seldom studied, especially using 0-DOF tools to operate and only force sensing to detect. A novel door-opening method for six-legged robots is developed and imple- mented to the six-parallel-legged robot. The kinematic model of the six-parallel-legged robot is established and the model of measuring the positional relationship between the robot and the door is proposed. The measurement model is completely based on only force sensing. The real- time trajectory planning method and the control strategy are designed. The trajectory planning method allows the maximum angle between the sagittal axis of the robot body and the normal line of the door plane to be 45°. A 0-DOF tool mounted to the robot body is applied to operate. By integrating with the body, the tool has 6 DOFs and enough workspace to operate. The loose grasp achieved by the tool helps release the inner force in the tool. Experiments are carried out to validate the method. The results show that the method is effective and robust in opening doors wider than 1 m. This paper proposes a novel door-opening method for six-legged robots, which notably uses a O-DOF tool and only force sensing to detect and open the door.
